Package wrapping and feeding mechanism



July 31, 1962 R. F. KENT ETAL 3,

PACKAGE WRAPPING AND FEEDING MECHANISM Filed Aug. 24, 1959 2 Sheets-Sheet 1 ATTOIPIVFVJ' July 31, 1962 R. F. KENT ETAL 3,046,715

PACKAGE WRAPPING AND FEEDING MECHANISM Filed Aug. 24, 1959 United States Patent 3,046,715 PACKAGE WRAPPING AND FEEDlNG MECHANISM Richard F. Kent and Harry H. Schafer, Bellingham,

Wash, assignors to Washington Packaging Corporation, Seattle, Wash, a corporation of Washington Filed Aug. 24, 1959, Ser. No. 835,596 25 Claims. (Cl. 53231) The present invention relates to improvements in package wrapping and sealing mechanisms and elemental arrangements therefor, and more particularly to means for receiving and conveying a partially wrapped package or packages with automatic compensation as to package height, so that uniformity of packaging is obtained irrespective of the particular height or top surface contour of the article material being packaged. Especial advantages are achieved by the mechanisms and arrangements of the present invention where the packaging involves so-called bottom folding of a transparent thermoplastic sheet about a flat card on which the material being packaged rests, i.e. the type of package commonly known as a fiat.

Various objects, features, characteristics and advantages of the invention and discovery include the provision of package wrapping, manipulating and sealing mechanism wherein package feeding mechanism manipulating the package during final stages of folding and sealing of the wrap include a pusher means designed to positively and effectively convey any form of pack but particularly a pack having only a flat card or shallow tray as the supporting member for the article or material being wrapped; wherein such pusher means is manipulated so as to be in a down position during the forward stroke of reciprocating package conveying means and is automatically elevated during at least the latter portion of the return stroke of the package conveying means to clear and drop behind the next oncoming package without disturbing the partially formed wrap on the latter, the manipulation of the pusher means being by simple cam means around which a portion of the pusher means passes cyclically; wherein the package feeding means further comprises downward pressure imparting means exerted on the top of the package being formed, such downward pressure means traveling along with and being slightly elevated above the package during most of the advancing movement of the package across initial fold seal means and final fold forming means, then pass to pressure exerting position on the top of the packaging as the package passes the final fold former and reaches a final fold sealer, the said pressure means by such action not interfering with or disturbing previously formed folds or disturbing the final folding operation; wherein means are provided for cyclically manipulating the said pressure means during reciproeating of the package feeding mechanism so as to accomplish cyclic elevation and downward release of the pressure means in the manner indicated, such pressure means manipulating mechanism including means automatically elevating said pressure means during the early portion of an advancing stroke and the late portion of a retraction stroke of the package feeding means, the pressure means further comprising downward loading and an assembly permitting substantial vertical movement of a pressure foot to accomplish such manipulation automatically and exerting a predetermined amount of pressure on the package being formed, regardless of the height of the package within a wide range; wherein reciprocating package feeding means and pusher and pressure means are provided which are constructed and function with maximum simplicity and reliability, and are simple to construct and maintain, as well as modify or adjust as production conditions require; and wherein a package feeding, wrapping and sealing mechanism is such as to be automatically adaptable to operate on certain package dimensions and readily adjustable so as to receive other package dimensions, and with the entire final folding and sealing operation being accomplished in a single path along a horizontal, straight line path of travel, i.e. by and during unidirectional movement of the package being formed. 7

These and other objects, features, characteristics and advantages of the mechanism and elemental arrangements of the invention will be apparent from the following description and accompanying illustrations of a typical and therefore non-limitive embodiment thereof, wherein like numerals refer to like parts, and wherein:

FIG. 1 is a somewhat diagrammatic isometric View of a partially folded flat package typifyin'g the package form and its partially wrapped character as the package is delivered into the infeed station of the final folding and sealing mechanism shownin FIG. 2, the view of FIG. 1 being from a lower aspect; 7

FIG. 2 is an isometric view, with certain portions shown broken away and exploded, of a final wrap and sealing mechanism characteristic of the invention, including the package feeding means and manipulating mechanism therefor, the view of FIG. 2 being from an upper and forward aspect looking at an angle into the outfeed end of the assembly;

FIGS. 3, 4, 5 and 6 are diagrammatic side views showing in simplified form the sequence of manipulation of the package feeding elements, and particularly the pusher plate, pressure shoe and associated cam mechanism;

FIG. 7 is a fragmentary view in front elevation of certain elements of the mechanism shown in FIG. 2, taken from the front or outfeed end, and further showing the arrangements of the trackway for the carriage mounting the pusher and pressure means and the lateral disposi tion of the cam elements of the assembly;

FIG. 8 is a fragmentary rear view of the pusher plate sub-assembly; and

FIG. 9 is a fragmentary view in side elevation of the pusher plate sub-assembly, the pressure foot sub-assembly, and the carriage mounting these assemblies, taken from the side reverse to that shown in FIG. 2.

Turning to a more specific consideration of the mechanism as illustrated in FIGS. 2 through 9, and the manner of operation thereof with respect to a unit such as a partially wrapped package such as shown in FIG. 1, it will be first observed that the partially wrapped package designated, generally at P is suitably of a type having a flat card 10 under the material or article 12, such as a meat cut or hamburger patty, being packaged, the transparent thermoplastic wrapping material generally designated at 14 being partially formed around the material 12 and card 10 with a first bottom fold 16 in place, and with certain corner tucks 18 and end folds 20 also formed or partially formed, the second bottom fold forming panel 22 of material 14 and the associated corner tucks along with the final bottom folds being as yet unfolded. At this point, and with respect to the form of partially folded package shown at FIG. 1, it is to be observed that such partial wrap form can be advantageously although not necessarily made by the preliminary package handling and wrapping stages of the'wrapping'mecha nism disclosed in Ingram US. Patent FIG. 1 of said Ingram. patent.

With the Ingram patent in view, and turning to a"co I1'-' sideration of the assembly shown in instant FIG'. 2, it

will be readily understood that the incoming package 'form shown here inFiG. 'l and also designated generally-at P" in our FIG. 2 can be prepared and delivered in the form shown by the Ingram mechanism, the manner of delivery being on a traveling table fragmentarily shown at 1 n our FIG. 2 (said traveling table being designated 112 in the Ingram patent), the direction of delivery being first as designated by arrow 32, then as designated by arrow 34, the manner of manipulation of package P being such that said package is deposited at the infeed point of the assembly shown in our FIG. 2, the mechanism for such manipulation being fully illustrated and discussed in said Ingram patent and incorporated by reference in this disclosure as a typical form of package prewrapprng and delivery mechanism, known per se. As will also be understood, the partially Wrapped package can be delivered to the mechanism shown in our FIG. 2 in any other appropriate manner, or can even be partially Wrapped and fed by hand.

With respect to the infeed manipulation of the incoming partially wrapped package P, it is also important to observe that the directional movement thereof oif traveling table 30 into the infeed station of the mechanism typifying the present invention, i.e. specifically in the direction of movement shown by the arrow designated at 34, involves movement of the package P past vertically extending end fold members and 42 and onto a heater plate 44, the said end fold members 40 and 42 folding the leading corners at the ends of package P and the movement of package P onto heater plate 44 serving to make the second bottom fold (of flap 22), the function of said heater 44 being to seal or at least partially seal the second bottom fold to the first bottom fold 16. The position of rest of package P, with the leading corner tucks and second bottom fold thereof just formed and the bottom folds at least partially sealed, i.e. the position of rest of package P on heater plate 44 after the infeed movement designated at 34, is termed the infeed station in the following description.

In connection with the following discussion of the elements and manner of operation of the mechanism characterizing the present invention as presented in the accompanying illustrations, reference should be made to the diagrammatic views presented at FIGS. 3-6 for the sequential relation of the elements, along with the various other figures further showing such relations and the constructional detail involved.

The illustrated mechanism comprises what may be termed a feed deck arranged horizontally in the area generally designated at 50, said feed deck including the aforesaid heater plate 44, a lateral pair of end fold down elements, one of which is shown at 52, a pair of laterally adjustable package end engaging fences designated at 54 and 56 which respectively carry end fold members 40 and 42 and end fold down element 52. Bottom fold forming elements 58 and 60 are also carried by fences 54 and 56. A further pair of bottom fold forming elements 62 and 64 are laterally adjustable with fences 54 and 56, and the bottom folding mechanism further includes a fixed bottom fold forming element 66. All of the said bottom fold forming elements 52-66 are generally conventional per se and collectively constitute what can be identified as a bottom fold forming station, the lateral adjustment of the end fences 54, 56 along with the elements 40, 42 and 52 carried thereby and elements 62 and 64 associated and laterally movable therewith being synchronously accomplished by means likewise known per se, such as that illustrated in FIG. 3 of said Ingram patent, the fences being designated 126 and 128 in the Ingram patent and the specific folding mechanism there shown being of the so-called end fold type. As will be apparent, the mechanism of the subject invention has equal utility for end-fold packaging operations, such as for so-called U-board packaging for example, in which event an end fold section replaces the bottom fold section shown in FIG. 2, suitable end-fold fences and associated elements to accomplish such adaptation being shown in FIGS. 3-5 of said Ingram patent.

Also constituting a portion of feed deck 51 are heater plate 70 and discharge platform 72 including a third heater plate 74. The said discharge platform 72 is pivoted on trunnions mounted on stationary frame member 76, one such trunnion being designated at 78, the outfeed slope of discharge platform 72 being thereby adjustable and supported by bracing (not shown) to meet whatever type of formed package receiving equipment is used in conjunction with the packaging mechanism. In one existing commercial installation, discharge platform 72 slopes downwardly about 5, for example.

The package feeding mechanism arranged to reciprocate over feed deck 50 involves a downwardly urged pressure shoe 80, pressure loaded as by spiral spring 82, and a vertically movable pusher means such as pusher plate assembly 84, said pressure plate assembly 84 and said pressure shoe 89 both being mounted for vertical movement on a horizontally reciprocated carriage 86 having lateral pairs of wheels 88 riding in opposed U-shaped trackways 90 and 92. The mechanism mounting pressure shoe 80 on carriage 86 includes guide sleeve 94, the slot 96 in said sleeve (see FIG. 9) receiving pin 98 at the top of stub shaft 160 which in turn mounts said pressure foot 89 at its lower end, the said pin 98 also being engaged by slot 192 in loading arm 104, said loading arm 194 being mounted for pivotal movement about pin 166 on spring mounting arm 108 depending integrally and forwardly as part of said carriage 86. As will be evident, spiral spring 82 has the inner end thereof anchored to pin 166 and its outer end anchored to pin 110 of loading arm 104 in a manner exerting a downward pressure on pin 23.

Also depending downwardly from carriage 86 is stub shaft 112 from which the pusher plate assembly 84 depends. Protruding from shaft 112 near the bottom thereof is a horizontally extending pin 114 (see FIGS. 8 and 9). The main body portion 116 of the pusher plate assembly 84 includes a guide sleeve 117 telescopable around pusher plate mounting shaft 112, with its normal position in the downward position shown in FIG. 2 being maintained gravitationally. Sleeve 117 is provided with slots 118 riding on pin 114. The front, flat face plate 119, preferably in the general form of an inverted T, has a vertically arranged slot also riding on pin 114, the said face plate 119 being attached as by welding to the edge of sleeve 117 with the slot 120 and the slots 118 aligned.

Trackways 90 and 92 are mounted in fixed position on and project forwardly from stationary framing box 122, in turn mounted in fixed position on stationary support member 124. Mounted laterally at the sides of stationary framing box 122 are a pair of chain frames 126 and 128 (also see FIG. 7), the rearward portion of chain 126 and 128 being interconnected by a web plate Cyclical reciprocation of carriage 86 is caused by linkage thereof through pin 132 to a lateral pair of arms 134 and 136 (said arm 134 and the adjoining portion of pin 152 being shown in an exploded position in the isometric view of FIG. 2 for clarity of illustration of other detail), thence through pins 138 and 140 respectively to a lateral pair of drive chains 142 and 144. Said drive chains 142 and 144 pass around forward sprockets on chain frames 126 and 123, the respective forward sprockets on chain frames 126 and 128 being shown at 146 and 147, and pass around rear sprockets at the rear of said chain frames 126 and 128, the rear sprocket on chain frame 126 being shown at 148, the drive chain assemblies further including upper and lower chain supporting guides, said guides as provided on chain frame 126 being respectively shown at 150 and 152. The rear sprockets, one of which is designated at 143, are keyed on a common shaft 154 having keyed centrally thereof a drive sprocket 156, in turn driven by chain 158 from sprocket 160 and its drive shaft 162, the rotational drive of said shaft 162, as indicated at 164, being at a speed and preferably derived from the drive gear box of the associated pre-wrapping mechainsm so that carriage 86 courses a reciprocation cycle in timed relation each time a pie-wrapped package is delivered to the infeed station 54) by the associated pre-wrapping mechanism.

Functionally, pressure shoe 30 and pressure plate assembly 84 are cyclically elevated from the forwardmost position thereof shown in the isometric view illustrated at FIG. 2 (and also FIG. 3) to a retracted position behind the next package deposited at the infeed station (confer FIG. 5) by action of two camways. The first such camway, designated at 170 and 170, can be termed a pressure shoe cam and receives cam follower pin 17 2 (see FIG. 9) on pressure shoe loading arm 184. As carriage 86 retracts from the position shown at KG. 2 by the retraction drive from chains 142 and 144, cam follower pin 172 rides up on camway 170 and 176 and pressure shoe 80 is elevated to -a position Where it is elevated above and clears the package arriving at the infeed station, progressively in the manner shown at FIGS. 4 and 5.

A pair of camways 174, 174' and 176, 176, which can also be designated pusher plate cam-ways, likewise serve to elevate the pusher plate 84 on retraction of carriage 556, in the following manner. Main body 116 of the pusher plate assembly 84 mounts cam follower pins 173 and 150 which ride up over said cams 174, 174 and 176, 176' during the retraction movement of carriage 86. Said cams 174 and 176 are of a length rearwardly (portions 174' and 176) so that when said carriage 86 is fully retracted, cam follower pins 178 and 1813 drop off cam surfaces 174 and 176' at the rear surfaces 174" and 176 thereof (com-pare FIG. 5, the direction of dropoff movement being indicated by the arrow 182). At this point the pusher plate assembly 84 drops behind the package at the infeed station, the carriage 86 being fully retracted. Also at this time the pressure shoe 80 is in an elevated position and cam follower pin 172 is in engagement with the fixed portion 170' of pressure shoe camway 170 and the pusher plate 84 has likewise been elevated, then dropped behind the package at the infeed station, the elements of the package feeding mechanism being at the time of full retraction thereof substantially in the position shown at FIG. 5.

Forward movement of carriage 86 from its point of full retraction then causes pusher plate 84 to move the package across heater plate 44, then across the bottom folding mechanism, then progressively onto heater plate 70 and heater plate 7 4. During the advancing movement of carriage 86, pusher plate 84 is at all times in a lowermost position. Pressure plate 89 during the earlier portion of the advance is at an elevated position above the package and moving along therewith. Then, as cam follower pin 172 moves down the sloping portion of pressure shoe cam 170, the action of spiral spring 82 acting through arm 194 continues to exert downward pressure on pressure shoe 8t) and in turn on the top of the package, the point of contact and application of pressure by pressure shoe St on the package varying somewhat with the height of the package and being essentially at the time the package is moving passed the bottom folding elements and onto heater plate 7 0. Thus, said pressure shoe 80 exerts its pressure substantially at and during the time the final fold has been made and is being sealed or about to be sealed by heater plate 7 0, but not before. This action represents an important feature of the invention because it achieves an adequate pressure downwardly on the package at the time its bottom folds are being sealed, regardless of the height of the package, and because it"exerts n0 sliding, upsetting disruptive pressure on the package during the time the bottom folds are being made. Further, the downward pressure is exerted by the pressure shoe 8% while the shoe '80 is moving 'with and at the same rate as the package, in contrast to certain prior arrangements Where downward pressure is exerted by a stationary element tending to remove or peel off the wrapping from the package by the relative slidable movement therebetween.

portion Then, as pin 172 follows down the sloping,

portion of cam 17%, the pressure shoe -86 comes into pressure engagement with the top of the package and moves forwardly therewith as the package moves across heater plate '79, i.e. through the bottom fold sealing sequence. This arrangement achieves a very desirable mode of manipulation of the package because the package is pressure loaded from the top by means moving forwardly with the package as it is being sealed. Such manner of manipulation is particularly advantageous with the type of pack: aging involving only a flat card at the bottom, as previously indicated, because any pressure device which has a sliding engagement with the Wrapping at the top of the package will tend to peel off the wrapping and/or disturb the package contents. Further, the pressure shoe mounting mid spring loading mechanism including spinal spring 32 has the additional and very practical feature of being automatically compensating as to height of the package. Use of a loadingmeans such as spiral spring 82 is of particular utility in this respect in that it provides a simple and substantially uniform loading throughout the wide range of vertical positions of pressure shoe 80. In an existing commercial installation, for example, the operative clearance of pressure shoe fit from the feed deck automatically adjusts in the range from about /2 inch to about 4% inches, and the pressure shoe loading mechanism can handle random assortments of thin cuts, such as chops or cube steaks, or thick patties such as hamburger packs of a thickness up to about 4 inches, all without any necessity for adjustment of the mechanism by the operator.

The forwardmost, sloping portions of camways 170, 174 and 176 are mounted for limited pivotal movement about pivot bolts 184 and 186, an extent of movement being permitted by slot means near the forward end of stationary cam plates 188 and 190. One of such slots is designated at 192 in plate 188 and the slots are dimensioned so that the movable cam segments 194, 195 and 196 are lifted out of the way of and ride over pusher plate cam following pins 178 and during the advancing stroke thereof, one point of lift being illustrated at FIG. 6.. After cam follower pins 178 and 180 clear the 'unde'rsurfaces of the pivoted cam segments 194, and 196, then saidncam segments 194-, 195 and 196 drop gravitationally to their lowermost position, ready to again receive the respective cam follower pins 172, 178 and 180 during the retraction stroke (again note FIG. 3).

By action of camways 174 and 176 the pusher plate assembly is elevated by cam follower pins 178 and' 180 riding thereover, and the elevated position is maintained 7 by cam surface portions 174 and 176', with the cam follower pins 178 and 180 dropping off at the rear ends 17 "f and 17 6" of said camways. The gravitational drop of the pusher plate assembly 84 at the rearwardmost position of reciprocating carriage 86 is preferably augmented by a compression spring 198 of short length arranged around shaft 112, the length and action ofsuch spring'being such 7 that it is compressed only when the pusher plate mounting block 116 is in its uppermost position, i.e. when cam follower pins 178 and 180 are riding on camway portions 174 and 176, such as 'inthe relative position thereof i1; lustrated at FIG. 4. Said spring 198 serves to impart posi-' tive downward urging to the pusher plate assembly as cam follower pins 178 and 180 clear the rearwardends of camway portions 174 and 176 to initially implement the gravitational tendency of the pusher plate assembly 84 to" fall to its lowermost position, and to'insure such movement with rapidity and certainty.

Further details of the various elements forming the feed deck 50 and the pusher plate assembly 84 which are particularly useful in handling packages of the so-called flat type, i.e. where only a flat card is used at the bottom of the package as when packaging cuts of meat, hamburger or the like, will now be discussed. In this type of packaging, serious ditficulty is encountered in the art in having a pusher mechanism pick up and move the fiat card without the card slipping under the pusher mechanism and without disruption of the article or material being packaged. To this end, the face plate 119 of the pusher plate assembly is provided with depending fingers 200 and the heater plates 44 and 70 are provided with respective slots 202 and 204, it also being noteworthy in this connection that the configuration of the bottom folding elements also provides alined clearance with said slots 202 and 204. As will be apparent, said depending fingers 200 on pusher face plate 119 ride in and just clear slots 202 and 204 during the advancing stroke of the pusher plate assembly 84, insuring that even when the package being advanced is of the type having only a flat card bottom panel, such flat card is at all times positively engaged by the pusher plate. In terms of clearance, a typical installation is designed so that the lower edge of pusher face plate 119 has a clearance of about of an inch with respect to the surface of heater plates 44 and 70, with the depending dimension of finger 200 being about 7 of an inch, the depth dimension of slots 202 and 204 also being about of an inch.

operationally, slotted heater plate 44 serves to tack the first and second bottom folds together and does so effectively for purpose of retaining the folds in proper relative position, the entire overlapping area of the bottom folds being sealed except for two small areas left by slots 202. As previously indicated, heater plate 70 functions to seal the final bottom folds imparted by elements 52 through 66, the sealing occasioned by heater plate 70 likewise being effective throughout the entire bottom area of the package, except for the two small areas left by slots 204. The function of the uniformly flat, third heater plate 74 is to repeat the bottom area sealing action and also to seal any small unsealed areas left by slots 202 and 204 while the formed package P rests on said heater plate 74. In one typical installation, the temperature at which heater plates 44 and 70 are operated is about 550 F., and the temperature at which heater plate 74 is operated is about 400 F. As will be evident, the dwell time of the formed package on heater plate 74 is longer than the dwell time of the formed package on heater plate 70, the formed package being deposited on heater plate 74 at the forwardmost extent of travel of carriage 86, the formed package resting on said heater plate 74 until the time of arrival of the next oncoming package moving across the feed deck 50, the next oncoming package pushing the previously formed package off heater plate 74 onto the outfeed area of discharge platform 72.

As will likewise be evident from the illustration thereof at FIG. 2, heater plates 44 and 7 are stationarily mounted to a lateral pair of frame members, the left hand frame member being indicated at 206. Thermostatically controlled energization of the heater plates 44, 70 and 74 from a suitable power source is by means conventional per se.

From the foregoing description and accompanying illustration of a typical embodiment of the features and characteristics of the invention, as well as various consideration given as to certain variations and modifications thereof, many other forms, variations, modifications and adaptations of some or all of the elements, arrangements, mode of operation and functional aspects characterizing the invention will readily occur to those skilled in the art within the spirit and scope of the following claims.

What is claimed is:

1. Wrapping mechanism comprising means delivering a unit being packaged to an infeed station on a feed deck for Wrapping as the package is conveyed along the feed deck, fold forming means along said feed deck, fold sealing heater means along said feed deck, and unit feeding means successively delivering units from said infeed station continuously past said fold forming means and said heater means, said unit feeding means comprising pushing means rectilinearly pushing the unit to advance the same and pressure means elevated over and moving along with the advancing unit as it passes said fold forming means and then moving continuously along with and exerting downward pressure on the top of the advancing unit when the package folds have been formed and are being sealed by said heater means, the said unit feeding means including a carriage and means rectilinearly reciprocating said carriage above said feed deck, and the said unit feeding means manipulating said pusher means during a return stroke of said carriage to be raised above a package at said infeed station.

2. A package wrapping mechanism comprising means delivering a partially wrapped package to an infeed station on a feed deck for further wrapping as the package is conveyed along the feed deck, fold forming means along said feed deck,'fold sealing heater means across said feed deck, and package feeding means successively delivering packages in continuous movement from said irneed station past said fold forming means and over said heater means, said package feeding means comprising pusher means rectilinearly pushing the package to advance the same and pressure means elevated over and moving with the advancing package as it passes said fold forming means and then moving continuously along with and exerting downward pressure on the top of the advancing package when the folds therein have been formed and are being sealed by said heater means, the said package feeding means including a carriage and means rectilinearly reciprocating said carriage above said feed deck, and the said package feeding means manipulating said pusher means during a return stroke of said carriage to be raised above a package at said infeed station.

3. A package wrapping mechanism comprising means delivering a partially wrapped package to an infeed station on a feed deck for further wrapping as the package is conveyed along the feed deck, fold forming means along said feed deck, fold sealing heater means across said feed deck, and package feeding means successively delivering packages in continuous movement from said infeed station past said fold forming means and over said heater means, said package feeding means comprising pusher means rectilinearly pushing the package to advance the same and pressure means elevated over and moving with the advancing package as it passes said fold forming means and then moving continuously along with and exerting downward pressure on the top of the advancing package when the final folds therein have been formed and are being sealed by said heater means, the said pres sure means including a pressure shoe and means downwardly loading the movement of said pressure shoe and mounting same for substantial vertical self-adjustment, whereby said pressure shoe means automatically accommodates and compensates for successive packages of various heights, the said package feeding means including a carriage and means rectilinearly reciprocating said carriage above said feed deck, and the said package feeding means manipulating said pusher means during a return stroke of said carriage to be raised above a package at said infeed station.

4. A package wrapping mechanism comprising means delivering a partially wrapped package to an infeed station on a feed deck for final wrapping as the package is conveyed along the feed deck, a first heater means on which said package rests when at said infeed station, fold forming means along said feed deck, a second heater means across said feed deck subsequent in the line of advance of the package past said fold forming means, and package feeding means successively delivering packages in continuous movement from said infeed station past said fold forming means and over said second heater means, said package feeding means comprising a pusher assembly having a pusher piate and means for reciprocatingly advancing the plate with and behind an advancing package and for elevating and dropping the plate behind the next oncoming package arriving at said infeed station, and pressure shoe means elevated over and moving along with the advancing package passing said fold forming means and then moving continuously with and exerting downward pressure on the top of the advancing package after the final folds therein are formed by said fold forming means and are being sealed by said second heater means.

5. Mechanism according to claim 4, further comprising means downwardly loading the movement of said pressure shoe and mounting same for substantial vertical self-adjustment, whereby said pressure shoe means automatically accommodates and compensates for successive packages of various heights.

6. Mechanism according to claim 5, wherein said means downwardly loading said pressure shoe comprises a spiral spring.

7. Mechanism for conveying a package across a feed deck while packaging operations are performed thereon, comprising a carriage arranged to be reciprocably and rectiline'arly driven over said feed deck, pusher means on said carriage, means on said carriage for exerting downward pressure on said package, means manipulating said pusher means so as to be elevated above the path of travel of a package during at least a portion of the return stroke of said carriage and for maintaining said pusher means at a lower position behind said package during the advancing stroke of said carriage, and means manipulating such pressure exerting means so that on the advancing stroke of said carriage the pressure exerting means is spaced above and moves along with said package for the first portion of the advancing stroke, then drops into pressure contact with the top of the package and moves continuously therewith during the latter portion of the advancing stroke.

8. Mechanism for packaging a package of the type having a flat card as a bottom panel, said mechanism including a generally fiat feed deck including folding mechanism and at least one heater plate over which the packages pass while final fold and fold sealing operations are performed thereon, a carriage arranged to be reciprocably and rectilinearly driven over said feed deck, pusher plate means on said carriage, and means on said carriage for exerting downward pressure on said package, means manipulating said pusher plate means so as to be elevated above the path of travel of a package during at least a portion of the return stroke of said carriage and for maintaining said pusher plate means at a lower position behind said package during a continuously advancing stroke of said carriage, and means manipulating such pressure exerting means in a manner so that on the advancing stroke of said carriage said pressure exerting means moves along with and spaced above said package for the first portion of the continuous advance then drops into pressure contact with and moves along with the top of the package during the latter portion of the continuous advance, the said pusher plate means'having depending elements designed .to ride below the general level of said feed deck on the advancing stroke of said pusher plate means, said feed deck being recessed to permit passage of said depending elements, the said depending elements functioning to insure that said pusher plate means is maintained in contact with the edge of the package bottom panel when advancing the package.

Y 9. Mechanism for conveying a package across a feed deckwhile, packaging operations are performed thereon,

comprising a carriage arranged to be reciprocably and continuously driven over said feed deck, pusher means on said carriage, and means on said carriage for exerting downward pressure on said package, means manipulating said pusher means so as to be elevated above the path of travel of a package during at least a portion of the return stroke of said carriage and for maintaining said pusher means at a lower position behind said package during the continuously advancing stroke of said carriage, and means manipulating such pressure exerting means so that on the continuously advancing stroke of said carriage the pressure exerting means is spaced above and moves along with said package for the first portion of the advancing stroke, then drops into pressure contact and moves dontinuously along with the top of the package during the latter portion of the advancing stroke, the means manipulating said pusher means and said pusher exerting means comprising camways over said feed deck, and cam followers on said pusher means and said pressure exerting means encountering said cam means so as to elevate said pusher means and said pressure exerting means during most of the retraction stroke of said carriage.

10. Mechanism according to claim 9, wherein said camways for manipulating said pusher means are of a configuration to elevate said pusher means during at least most of the latter portion of the return stroke of said carriage, then allow said pusher means to drop gravita-- tionally behind said cam means at the rearwardmost point of travel of said carriage.

ll. Mechanism'according to claim 9, wherein said camways for manipulating said pusher means are of a configuration to elevate said pusher means during at least most of the latter portion of the return stroke of said carriage, then allow said pusher means to drop gravitationally behind said cam means at the rearwardmost point of travel of said carriage, the forwardmost segments of said cam means being pivotally mounted so that said cam means ride over the cam follower means on said pusher means during the advancing stroke of said carriage, the said cam segments dropping to initial position after passage of the pusher means cam followers so as to receive said cam followers along the upper surfaces of said segments when said carriage again retracts.

12. A package wrapping mechanism particularly designed to fold and seal transparent thermoplastic sheet about a flat card -type bottom panel, said mechanism comprising a feed deck having, in the order they are encountered by a continuously advancing package, a first heater plate, final fold forming mechanism, and a second heater plate, said mechanism also comprising package feeding means including a'pusher plate continuously advanced during a feeding stroke and manipulated to be in a position just slightly spaced from said feed deck on a feeding stroke and to be elevated well above said feed deck during at least a portion of its retraction stroke then return to lower position behind the next oncoming package, said first and second heater plates having downwardly recessed slot means therein and said pusher plate having depending finger means thereon fitting into and spaced slightly in said slot means when said pusher plate is in advancing position.

13. Mechanism according to claim 12, wherein said slotmeans comprises a laterally spaced pair of slots and said finger means on said pusher plate comprises a laterally spaced pair of fingers mating with said slots when said pusher plate is in advancing position.

l4. Mechanism according to claim 13, wherein said package feeding means further comprises a pressure shoe moving continuously along with and exerting downward pressure on the package as the package passes over said second heater plate.

15. Mechanism according to claim 14, wherein said pusher plate and said pressure shoe are carried on a common carriage reciprocably and rectilinearly driven over said feed deck.

- 16. A package wrapping, mechanism particularly designed to'fold and seal transparent thermoplastic sheet about-a fiat card type bottom panel, said mechanism comprising a feed deck having, in the order they are encountered by a continuously advancing package, a first heater plate, final fold forming mechanism, a second heater plate, and a third heater plate; said wrapping mechanism also comprising package feeding means including a pusher plate continuously advanced during a feeding stroke and manipulated to be in a lower position just slightly spaced from said feed deck on a feeding stroke and to be elevated well above said feed deck during at least a portion of its retraction stroke so as to pass over and return to lower position behind the next oncoming package, said first and second heater plates having downwardly recessed slot means therein and said pusher plate having depending finger means thereon fitting into and spaced slightly in said slot means when said pusher plate is in advancing position, the said third heater plate being fiat in its full dimension laterally of the path of travel of the package so as to seal any fold areas not sealed because of the slot means in said first and second heater plates.

17. Mechanism according to claim 16, wherein said slot means comprises a laterally spaced pair of slots and said finger means on said pusher plate comprises a laterally spaced pair of fingers mating with said slots when said pusher plate is in advancing position.

18. Mechanism according to claim 17, wherein said package feeding means further comprises a pressure shoe moving continuously along with and exerting downward pressure on the package as the package passes over said second heater plate.

19. Mechanism according to claim 18, wherein said pusher plate and said pressure shoe are carried on a common carriage reciprocably and rectilinearly driven over said feed deck.

20. The combination in a package wrapping mechanism of means delivering a partially wrapped package to a feed deck preparatory to completion and sealing of the package Wrap as it passes along said feed deck, heater plate means at the entrance to said feed deck, a fold completing assembly in said feed deck, second heater plate means for sealing the completed folds of the package as it leaves said fold completing assembly, and reciprocating package feeding means successively delivering packages continuously across said feed deck and for applying continuous downward pressure to each package as it rests on said second heater plate means, said package feeding means comprising a vertically movable pusher plate, a downwardly loaded pressure shoe moved continuously along with the package during advance thereof and cam means operating to cyclically manipulate said pusher plate to a down position behind a package on the forward stroke of said package feeding means and to an elevated position on at least a portion of the return stroke of said package feeding means so as to elevate above, clear and drop behind the oncoming package at the infeed station, said cam means also operating to cyclically manipulate said pressure shoe to an elevated position spaced above the package during the initial portion of the forward stroke of said package feeding means and to a downward pressure exerting position on the top of the advancing package as the package reaches said second heater plate means.

21. In a package wrapping mechanism, means delivering a partially wrapped package to an infeed station for final wrapping as the package is conveyed along a feed deck, end fold and bottom fold forming means along said feed deck, heater means across said feed deck, and package feeding means successively delivering packages from said infeed station in continuous movement past said fold forming means and over said heater means, said package feeding means comprising a pusher plate and means by which the pusher plate is cyclically advanced with and behind the advancing package and elevated and dropped behind the next coming package arriving at said infeed station, and pressure shoe means elevated over and mov- 12 ing along with the advancing package passing over said heater plate means and said fold forming means, and moving along with and exerting downward pressure on such continuously advancing package only when the final folds therein are formed and being sealed.

22. In a package wrapping mechanism, means delivering a partially wrapped package to an infeed station for final wrapping as the package is conveyed along a feed deck, end fold and bottom fold forming means along said feed deck, heater plate means across said feed deck, and package feeding means successively delivering packages in continuous movement from said infeed station, past said fold forming means, and over said heater plate means, said package feeding means comprising a pusher plate and means by which the pusher plate is cyclically advanced with and behind the advancing package and elevated and dropped behind the next coming package arriving at said infeed station, and pressure shoe means elevated over and moving along with the continuously advancing package passing over said heater plate means and said fold forming means and exerting downward pressure on said advancing package only when the final folds therein are formed and being sealed, the said pressure shoe being downwardly loaded and mounted for substantial vertical movement whereby said pressure shoe automatically accommodates and compensates for succesisve packages of various heights.

23. Mechanism according to claim 22, wherein said pressure shoe is operatively self-compensating for package heights in the range from about one-half inch to at least about four inches.

24. Mechanism according to claim 23, wherein the pressure shoe mounting means comprises loading means including a spiral spring delivering substantially uniform loading pressure to said pressure shoe throughout its operative range of adjustment.

25. In combination with package wrapping mechanism having means delivering a partially wrapped package to an infeed station preparatory to completion and sealing of the package wrap, a fold completing and sealing stage comprising a feed deck providing a path of travel for the package, heater plate means at the entrance to said feed deck, a fold completing assembly in said feed deck, heater plate means for sealing the completed folds of the package, and reciprocating package feeding means successively delivering packages across said feed deck in continuous movement and for applying downward pressure to each package as it rests on the second-mentioned heater plate means, said package feeding means comprising a vertically yieldable pusher plate, a downwardly loaded pressure shoe moved continuously along with the package during advance thereof, and cam means operating to cyclically manipulate said pusher plate to a down position behind a package on the forward stroke of said package feeding means and to an elevated position on at least a portion of the return stroke of said package feeding means so as to elevate above, clear and drop behind the oncoming package at the infeed station, said cam means also operating to cyclically manipulate said pressure shoe so as to be in an elevated position over the package during the forward stroke of said package feeding means and to contact and exert continuous downward pressure on the advancing package while moving along therewith as the package reaches said second-mentioned heater plate means.

References (Iited in the file of this patent UNITED STATES PATENTS 1,575,723 Smith et al. Mar. 9, 1926 2,283,097 Sandberg May 12, 1942 2,653,433 Sandberg Sept. 29, 1943 2,699,022 Wollett Jan. 11, 1955 2,801,508 Prince Aug. 6, 1957 2,860,466 Ingram Nov. 18, 1958 

